Strong caution about reading the US Custom rules for declaring goods and services bought externally when going through the border. Don't do it. Following the rules literally is an impossible task. My first re-entry was while transiting from Japan to Saudia Arabia through Louisana and the declaration for the family 15 bags of luggage was 7 pages long. Custom agent suggested that we rewrite the document to a couple items that was covered under the exclusion, create less work and not suffer import duty. Fast forward after working internationally 25 years later at the Progresso border crossing, I had two bottles of liquior declared when one was allowed. I asked to pay the duty and was told to move on, pay the state tax on the two and not create work. The rules are written to be absolutely comprehensive and are enforced to prevent the serious stuff, like money laundering, gun running and drugs. Be sure to declare something to have a conversation with the agent, for his ability to evaluate you.IE dogs, ownership paper for vehicles, absence of fresh vegies and meat etc. He/she will not be interested in how many pair of new underwear you have on board.
pops